Please review this test-only change. tools/jlink/multireleasejar/JLinkMultiReleaseJarTest.java
This test fails intermittently on Windows platform in the final cleanup step, @AfterClass, in which test tries to delete all dirs and files it created. Though it’s okay to leave this cleanup work to jtreg, I still make it done in test by making test to create everything under ./testoutput (testdir), and delete this testdir directly with FileUtils.deleteFileTreeWithRetry(testdir).
Moreover, in FileUtils, as it tries to delete path with retry, we might want to give it a chance to "retry" in case of DirectoryNotEmptyException.
bug: https://bugs.openjdk.java.net/browse/JDK-8169971 webrev: http://cr.openjdk.java.net/~amlu/8169971/webrev.00/ Thanks, Amy
